if this isn't a known issue, lemme do some more investigating. my test client
becomes "more random" with reads as time progresses, so possibly this is what
causes the latency issue. however, all that being said, the performance really
becomes bad after a while.
________________________________________
From: Brian Burruss
Sent: Sunday, December 13, 2009 1:14 PM
To: cassandra-user@incubator.apache.org
Subject: read latency creaping up
i've noticed the longer i let my test clients run the higher the read latency
becomes. if i kill the clients, the latency drops back down to a reasonable
value. write latency isn't affected. here are two cfstats listings from the
same machine, the first before and the second after i killed the clients. i do
not touch the servers. this seems odd. if the clients are doing some bad, it
seems that the server's latency wouldn't be affected. is this a thrift issue?
before
---------
Keyspace: uds
Read Count: 2003
Read Latency: 59.807 ms.
Write Count: 65145
Write Latency: 0.047 ms.
Pending Tasks: 0
Column Family: bucket
Memtable Columns Count: 168751
Memtable Data Size: 351695390
Memtable Switch Count: 94
Read Count: 2003
Read Latency: 59.807 ms.
Write Count: 65176
Write Latency: 0.047 ms.
Pending Tasks: 0
after
-------
Keyspace: uds
Read Count: 53249
Read Latency: 3.653 ms.
Write Count: 52888
Write Latency: 0.035 ms.
Pending Tasks: 0
Column Family: bucket
Memtable Columns Count: 383297
Memtable Data Size: 798864312
Memtable Switch Count: 94
Read Count: 53271
Read Latency: 3.649 ms.
Write Count: 52937
Write Latency: 0.035 ms.
Pending Tasks: 0
